Automated voice over IP device VLAN-association setup

ABSTRACT

A system and method are disclosed for automatically registering various system attributes with a VoIP device such as an VoIP phone. The system attributes are provided by a network, preferably an adjacent switching device made aware of the system attributes through one of a number of learning mechanisms. The system attributes may include one or more of the following: the VLAN identification used for VoIP communications in the subnet in which the VoIP phone is connected; the switching device identification, switching device slot, and switching device port number to which the VoIP phone is connected. The switch, slot, and port are used in some embodiments by an IP PBX system to construct a relational database that associates the geographic location of the connection with the IP phone for purposes of reporting the physical location of the VoIP user to emergency response personnel. The system and method for automatically registering various system attributes enables the relational database to be updated prompt and accurate.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. provisionalapplication serial No. 60/437,215, entitled “COMMUNICATION NETWORKHAVING IP PHONE LOCATION ASSOCIATION,” filed Dec. 31, 2002, the contentsof which is hereby incorporated herein by reference for all purposes.

FIELD OF INVENTION

[0002] The invention relates to Voice-over-Internet Protocol (IP)technology used to manage Voice-over-IP devices in a distributednetwork. In particular, the invention relates to a system and method forautomatically transmitting system attributes including the Virtual LocalArea Network (VLAN) identifier and physical connectivity informationfrom a network node to a Voice-over-IP device.

BACKGROUND

[0003] When building data networks to support voice-over-IP (VoIP)communications it is often desirable to place the IP Phones in aseparate VLAN from the other data devices in the network. This makes iteasier for the switches in the network to provide the Quality of Serviceprocessing needed to ensure proper transmission of VoIP calls. Theswitches in the network are configured with the VLAN dedicated for VoIPtraffic. The VLAN to which an IP phone belongs is identified using anIEEE 802.1Q tag with the VLAN value in the Ethernet frames, for example,generated by the device. After being assigned, the VLAN value is placedin the header of substantially all frames transmitted by the IP phone.

[0004] Unfortunately, the current protocols defined for distributingVLAN information between switches do not provide a mechanism to informend users which VLAN should be used for purposes of sending traffic. TheVLAN identification must therefore be manually configured in each VoIPphone either directly or through a network management tool. Suchpractices are both time consuming and raise the potential for humanerror. To add to the burden, it may be necessary to reconfigure an IPphone with a new VLAN if the IP phone is moved to a different switch orif the VoIP VLAN configuration of the switch is changed.

[0005] There are mechanisms for distributing information betweenswitches about the VLANs configured on the respective switches and fordistributing the information between switches to construct a topologicmap of the network, for example. The Group Address

[0006] Resolution Protocol (GARP) VLAN Address Resolution Protocol(GVRP) standardized by the IEEE in IEEE Standard 802.1Q-1998-IEEEStandards for Local and Metropolitan Area Networks: Virtual BridgedLocal Area Networks provides a mechanism for conveying informationbetween switches in the network about the IEEE 802.1Q VLANs configuredon the switches and on which ports of the respective switches theseVLANs are configured. In particular, the IEEE 802.1Q standard defines anarchitecture for Virtual Bridged LANs, the services provided in VirtualBridged LANs, and the protocols and algorithms involved in the provisionof those services. However, no such mechanism has been defined forcommunicating VLAN configuration information from a network device to anend system.

[0007] In addition to communicating VLAN configuration information to aVoIP phone, it is also desirable to communicate physical locationinformation from the phone to an IP private branch exchange (PBX).Enhanced 911 solutions, for example, require that phone systems such asIP PBXs provide physical location information with a 911 call using amechanism called the automatic location indicator (ALI). The ALI allowsan emergency service provider to automatically determine the physicallocation of the person placing the 911 call. The current state of theart for associating physical location information with the phone numberthat identifies a telephone uses an external database. The PBX thenconsults this external database when processing a 911 call to extractthe physical location information associated with the telephone placingthe 911 call. The location information in the external database must bemanually entered and is inaccurate when a phone is moved to newlocations in the network until the database is manually updated.

[0008] There is therefore a need for a system and method toautomatically communicate VLAN information to IP phones and toautomatically convey physical connectivity information to a centralstore with minimal human intervention, minimal delay, and maximalaccuracy.

SUMMARY

[0009] The invention according to the preferred embodiment features amethod that comprises steps for exchanging system attributes between atleast one VoIP device and another node in the network. In someembodiments, the VoIP device is an IP phone and the node to which it isoperatively coupled is an adjacent switching device or other addressableentities embodied in a processor, computer, or other appliance. The VoIPphone is preferably one of a plurality of devices that cooperate with anIP PBX employed in an enterprise network, for example.

[0010] The system attributes transmitted between the IP phone and othernodes may include, but are not limited to, one of the following: theVLAN identification of a VoIP VLAN assigned in the network, theswitching device identification, slot number and port number to whichthe IP phone is connected. The identification, slot number, and portnumber may also be communicated to the IP PBX where they are used torelate the physical location of the port connection with the IP phone towhich it is connected. The transmission of system attributes occursautomatically upon one of several triggering events, thereby avoidingthe need for manual configuration of the system attributes.

[0011] In the preferred embodiment, the system attribute exchangecomprises two messages, namely a first message referred to herein as aVoIP device identification message generated by the VoIP device, and asecond message referred to herein as a VoIP device identificationacknowledgment provided by the appropriate node in response. The VoIPdevice identification message notifies the node that the device is infact a VoIP device for which a VLAN assignment is warranted. Inresponse, the node automatically transmits the VoIP deviceidentification acknowledgment including the one or more systemattributes. In some embodiments, the VoIP device identification messageis generated automatically when (a) the IP phone is operatively coupledto the network, generally at the time it is initialized, or (b) theswitching device is initialized. In the later case, the VoIP deviceidentification message may be automatically transmitted in response to anode initialization message, i.e. a switching device notificationmessage that elicits identifying information from adjacent devices.

[0012] The invention in some embodiments features a system forperforming the connectivity-information exchange. The system generallyincludes at least one VoIP device such as an IP phone and a networkdevice such as a switching device. The VoIP device and node are adaptedto automatically send the VoIP device identification message and VoIPdevice identification acknowledgment in the manner described herein.With the system for performing the connectivity-information exchange,the VoIP VLAN to which the VoIP device is intended may be configuredautomatically with minimal or no manual intervention, thereby reducingthe labor necessary to configure the VoIP network. The absence of humanintervention may also increase the accuracy of a relational databaseused to report the physical location of an IP phone user to emergencyresponse personnel, as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, and in which:

[0014]FIG. 1 is a distributed network topology with which the preferredembodiment of the present invention may be implemented;

[0015]FIG. 2 is a flow diagram illustrating a system attribute exchangebetween an IP phone and switching device upon initialization of the IPphone, according to the preferred embodiment of the present invention;

[0016]FIG. 3 is a flow diagram illustrating a system attribute exchangebetween an IP phone and switching device when the switching device isinitialized or when the switching device detects that a new device hasbeen connected to a port of said device, according to the preferredembodiment of the present invention; and

[0017]FIG. 4 is a packet definition with which the VoIP deviceidentification message and VoIP identification acknowledgement may begenerated, according to the preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] Referring to FIG. 1, a distributed network topology with whichthe present invention may be implemented is illustrated. The networktopology 100 comprises one or more subnets 110, which may include anintranet, a local area network (LAN), a wide area network (WAN), or ametropolitan area network (MAN), and/or the Internet, for example. Thesubnet 110 associated with the IP phone 102 is preferably an Ethernetnetwork. Operably connected to the subnet 110 are a plurality of networkdevices including one or more VoIP communication devices 102, an IP PBX104, and a switching device such as a bridge or router adapted toperform layer 2 and/or layer 3 switching operations as defined in theOSI network model.

[0019] The VoIP device in the preferred embodiment is an IP phone thatoperates in cooperation with the IP PBX 104 and/or other VoIP devices(not shown) using the Session Initiation Protocol (SIP), Real TimeProtocol (RTP), or suitable alternative voice communication protocol.The IP phone 102 communicates indirectly with the IP PBX 104 by means ofthe switching device 108. As prescribed herein, the switching device 108facilitates the formation and maintenance of an audio communicationsession between the VoIP communication device 102 and the IP PBX orbetween two VoIP communications devices 102. In some embodiments, thecommunication session also supports audio and video communicationsessions.

[0020] In the preferred embodiment, the IP phone 102 is enabled with aVLAN tagging protocol, preferably 802.1Q or suitable equivalent, forpurposes of incorporating a VLAN identifier (VID) in outgoingtransmissions. The 802.1Q tag may be inserted by a software stack in theIP phone or by a network interface card, for example.

[0021] In prior art systems, the VID used by the IP phone 102 wouldnecessarily be manually configured by the network administrator, whichis both labor intensive and subject to human error. To overcome theselimitations, the several embodiments disclosed herein provide amechanism to automatically initiate an exchange referred to herein asthe system attribute exchange. The system attribute exchange includesone or more messages or transmissions between the VoIP device 102 andthe adjacent switching device 108 for purposes of distributing one ormore system attributes to the VoIP device, including the appropriateVID, to be used by the device for VoIP communications. In someembodiments the system attributes comprises the VID used for VoIPcommunications, although the system attribute exchange may furtherconvey information pertaining to the switching device identification,slot number, and port number associated with the IP phone 102.

[0022] The connectivity-information exchange may be initiated when theIP phone 102 is connected to the subnet 110 and initialized, when theswitching device 108 is initialized, or when the switching device firstdetects the presence of a device, such as IP phone 102 connected to oneof the switch ports.

[0023] Illustrated in FIG. 2 is a flow diagram of a system attributeexchange with an IP phone upon initialization of the IP phone. The IPphone 102 is initialized in step 204 when the phone is plugged into thenetwork 110. This may occur when the phone is first coupled to thesubnet 110 or when the IP phone is relocated in the subnet 110. In bothcases, the IP phone 102 transmits a VoIP device identification (VDI)message 206. In this embodiment, the VDI message 206 is the first of aplurality of transmissions that constitute the system attributeexchange.

[0024] The primary purpose of the VDI message 206 is to announce thepresence of the IP phone 102, i.e. to identify the IP phone 102 as aVoIP device to the adjacent switching device 108. The identity of thedevice as a VoIP device is important for purposes of including the IPphone 102 in the VLAN reserved for VoIP, and incorporating the IP phone102 into the switching device's forwarding tables as soon as isreasonably possible. After the adjacent switching device 108 is providednotice of the installation of the IP phone 102, the IP PBX is also madeaware of the presence of the IP phone 102 by means of a separate messageexchange between the IP phone and the PBX, for example..

[0025] In the preferred embodiment, the VDI message 206 is generated bythe IP phone 102 using what is referred to herein as an AttributeAdvertisement Protocol (AAP). AAP may be used to communicate informationincluding the VID or other attributes between AAP-enabled networkdevices such as the IP Phone 102 and adjacent switching device 108.Although AAP may incorporate one or more standard protocols, it isgenerally a localized solution supported by network devices of specificvendor using a non-standardized signaling convention enabled on variousdevices of the vendor. An advertisement protocol that may be adapted forpurposes of this invention is taught in copending U.S. patentapplication Ser. No. 10/028,647, entitled “VLAN Advertisement Protocol,”hereby incorporated by reference herein.

[0026] The VDI message 206 of the preferred embodiment, illustrated inFIG. 4, comprises an AAP version number, AAP type, VLAN identification,source port, media access control (MAC) address, flag field, IP addresscount and IP address, source host name, and clustering information. Thepurposes of the fields of the VDI message 206 are as follows:

[0027] a) Version number 402, preferably one byte, is assigned a valueto distinguish it from other AAP packet versions;

[0028] b) AAP type field 404, preferably one byte, is used todistinguish the AAP message as being a VDI message from other AAPmessage types;

[0029] c) VID 406, preferably 2 bytes, is generally used to designatethe VLAN of the device identified by the MAC address field, whichassigned a value of zero since it is unknown to the IP phone 102 at thetime of transmission;

[0030] d) Source Port 408, preferably two bytes, is generally used tospecify the port on the switch to which the phone is attached. Typicallythis is the slot number and port number where the IP phone is attached,but is assigned a value of zero since it is inapplicable to the IP phone102;

[0031] e) Reserved 410, two bytes herein, is unused in the presentembodiment;

[0032] f) MAC Address 412, 414, preferably six bytes, is used to specifythe MAC address of the source device, IP phone 102;

[0033] g) Flags 416, preferably one byte, assigned the value zero for aninitial VDI packet;

[0034] h) IP Address Count 418, preferably one byte, identifies thenumber of IP addresses contained in the frame, typically this isassigned a value of one;

[0035] i) IP Addresses 420, preferably multiple of four bytes, is usedto specify the IP address(es) of the device identified by the MACaddress. In the case of the IP phone this will typically be all zerosfor the initial message;

[0036] j) Source Host System Name 422, preferably 32 bytes, is used tospecify the name of source device, IP phone 102; and

[0037] k) Reserved 424, 16 bytes, is used in other AAP messages but notin VDI messages.

[0038] In the preferred embodiment, the VDI message 206 is incorporatedinto a packet having a special unicast MAC address since the MAC addressof the switching device 108 is unknown to the IP phone 102 at the timeof transmission. The MAC address used in some embodiments,00-20-DA-00-70-04, is reserved for AAP communications between devicespre-configured to recognizes this address. Alternatively, a broadcastaddress of FF-FF-FF-FF-FF-FF can be used as the destination MAC address.Upon receipt, the frame including the AAP header 400 is forwarded to anAAP processing agent in the switching device 108 responsible forrecognizing incoming AAP frames and generating the appropriate response.

[0039] When received, the switching device 108 forwards the VDI message206 to software where the source device is determined to be a VoIPphone. In addition, the switching device also determines that the VDImessage 206 is an introduction, in a manner of speaking, to which itmust respond with further information. The response, generated in step220, is a “VDI acknowledgement” 208 that informs the IP phone 102 of theVLAN configuration in the switching device 108 for VoIP traffic and the802.1Q value assigned to this VLAN, namely the VID 402. The VLANspecified by the switching device 108 to the IP phone 102 is preferablythe only VLAN dedicated to VoIP within that particular segment of thesubnet, although one skilled in the art will recognize that multipleVLANs may be set aside within an enterprise for voice data.

[0040] In the preferred embodiment, the VDI acknowledgement 208 furtherincludes “connectivity information” which, when associated with thegeographic distribution of the nodes of the network 106, can be used togeographically pinpoint the location of the IP phone 102. In thepreferred embodiment, the connectivity information includes, but is notlimited to, the switching device identification as well as the portidentification including, for example, slot number and port number onwhich the IP phone 102 connects to the switching device 108. The VLANinformation and the connectivity information described above arepreferably communicated to the IP Phone 102 in the same packet, althougha plurality of packets may also be employed. In addition, the VLAN usedfor VoIP is known to the switching device 108 as a result of one or moreconfiguration messages entered via the switch console or received from anetwork management entity.

[0041] The VDI acknowledgement 208 of the preferable embodimentcomprises an AAP version number, AAP type, VLAN identification, sourceport, MAC address, flag field, total IP address and IP address, sourcehost name, and clustering information. The purposes of the fields of theVDI acknowledgement 208 fields are as follows:

[0042] a) Version number, preferably one byte, is assigned a value todistinguish it from other AAP packet versions;

[0043] b) AAP type, preferably one byte, is used to distinguish the AAPmessage as being a VDI message from other AAP message types;

[0044] c) VID, preferably 2 bytes, is used to designated the VLAN (ordefault VLAN of port) to be used by the VoIP device in itstransmissions;

[0045] d) Source Port, preferably two bytes, is used to specify the portinformation, preferably source slot and port value to which the phone isattached;

[0046] e) Reserved, two bytes herein, is unused in the presentembodiment;

[0047] f) MAC Address, preferably six bytes, is used to specify themedium access control (MAC) address of the source device, namely theswitching device 108;

[0048] g) Flags, preferably one byte, assigned the value of one for areply packet;

[0049] h) IP Address Count, preferably one byte, identifies the numberof IP addresses contained in the subsequent fields, it is typicallyassigned a value of one;

[0050] i) IP Addresses, preferably multiple of four bytes, is used tospecify the IP address of the switching device 108;

[0051] j) Source Host System Name, preferably 32 bytes, is used tospecify the name of source device, namely the system name of theswitching device 108; and

[0052] k) Reserved 424, 16 bytes, is used in other AAP messages but notin VDI messages.

[0053] The VDI acknowledgement 208 in the preferred embodiment uses thesame frame format as that of the VDI message 206 with the appropriatemodification of the values, as described immediately above. The VDIacknowledgement frame can be sent as a broadcast packet or with the MACaddress of the IP phone as received in the initial frame from the IPphone.

[0054] Upon receipt of the VDI acknowledgement 208, the IP phone 102makes a record of the VID. The VID is then included in subsequentcommunication VoIP communications until the VLAN is reconfigured or theIP phone re-initialized in another location having a different VoIPVLAN. These communications including incoming and outgoing callsinitiated with connection request messages 210, 212 which, if answered224 by the call recipient coupled to the IP-PBX 104 or public switchedtelephone network (PSTN) (not shown) result in connectionacknowledgements 214, 216 that give rise to the voice communicationmessages 218A, 218B.

[0055] If the VDI acknowledgement 208 further includes the connectivityinformation or other system attributes, the IP phone 102 can directly orindirectly convey this information to the IP PBX 104 or alternativephysical locality mapping device. The IP PBX 104, for example, includesin some embodiments a relational database 106 having one or more tablesthat associate the switch, slot, and port numbers with the knowngeographic distribution of the nodes of the network 106. The database106, which is preferably automatically updated with the initializationor installation of all VoIP devices, provides real-time access to thephysical location of the IP phone 102 and substantially all other VoIPdevices in the subnet 110. The database 106, or IP PBX 104 moregenerally, outputs the physical location of an individual IP phone 102upon entry of one or more of the following: the device's extensionnumber as known by the IP PBX, MAC address, switching deviceidentification, slot number, and/or port number.

[0056] The embodiment of the invention therefore provides a method andsystem for automatically updating the VID of substantially all the VoIPdevices in a subnet. The present invention represents a significantimprovement over prior art systems that rely on the manual entry of aVoIP VLAN configuration which are prone to errors and are potentialincorrect for some period of time after an IP phone is move, added, orotherwise changed.

[0057] A further embodiment encompasses a system and methodincorporating IEEE 802.1x, which provides a control and authenticationmechanism to regulate access between the IP phone 102 and switchingdevice 108. Using an Extensible Authentication Protocol (EAP), forexample, one or more of the messages exchanged between the IP phone 102and the switching device 108 may comprise a machine credential used incooperation with an authentication server to regulate access to theother. The IP phone 102 may be programmed or hardwired with thecredentials needed by the authentication server for verification andassignment of a VoIP VLAN, or the VLAN assignment passed in an 802.1xmessage returned to the IP phone 102.

[0058] A further embodiment of the invention provides a method forproviding physical connectivity information to VoIP devices to allow forautomatic creation and updating of databases that contain the physicallocation of a given IP phone. A common practice relies on manualupdating of this data base and as a consequence, prior art system mayprovide inaccurate physical location information with a 911 call,thereby resulting in a possible delay in the arrival of emergencypersonnel. The ability to quickly, accurately, and unambiguouslyphysically locate a person in an emergency response situation clearlyhas life and death consequences.

[0059] In a second embodiment of the invention illustrated in FIG. 3,the system attribute exchange is first initiated by the switching device108 upon initialization which generally includes start up, boot up,installation, and re-installation. After the switching device 108 isinitialized during the initializing step 304, the switching device 108automatically generates a switching device initialization (SDI) message305 that is transmitted out of each of its interfaces. The SDI message305 elicits a response from adjacent devices for purposes of building orupdating the connectivity tables used by the switching device 108. Inthe preferred embodiment, the SDI message 305 uses the same frame formatas that of the VDI acknowledgement 208 with suitable modification of thevalues contained therein.

[0060] In response to the SDI message 305, the IP phone 102 preferablygenerates a VoIP device identity message, preferably VDI message 306, asillustrated in identifying step 302. The VDI message 306 issubstantially equivalent to the VDI message 206, the principal exceptionbeing that the destination address of the packet includes the MACaddress of the switching device 108 instead of the special purpose AAPMAC address.

[0061] The switching device 108 responds in the acknowledging step 322to the VDI message 306 with a VDI acknowledgement message 308. Theswitching device 108, which now knows the identity of the IP phone 102,preferably transmits the appropriate VID and, in some embodiments,additional connectivity information. The VDI acknowledgement 308 in thepreferred embodiment is substantially identical to the VDIacknowledgement 208.

[0062] Similar to the previously described embodiment, the completion ofthe system attribute exchange lays the foundation for subsequent voicecommunication 318A, 318B pursuant to an incoming call or outgoing callestablished by connection request messages 310, 312 and the connectionacknowledgement messages 314, 316, when the call is answered 324 by arecipient (not shown). Again, the connection requests messages 310, 312and the voice communication messages transmitted to the IP PBX 104include the VID provided by the switching device 108 in the VDIacknowledgement 308. The switching device 108, in turn, is programmed inthe VoIP VID by the network administrator or learned from another nodein the network 106 by means of a VLAN registration message 302.

[0063] Although the description above contains many specifications,these should not be construed as limiting the scope of the invention butas merely providing illustrations of some of the presently preferredembodiments of this invention.

[0064] Therefore, the invention has been disclosed by way of example andnot limitation, and reference should be made to the following claims todetermine the scope of the present invention.

We claim:
 1. A system attribute exchange method for automaticallyproviding at least one system attribute to one or more devices in anetwork, the method comprising the steps of: (a) automatically sending adevice identification message from the one or more Voice-over-IP devicesto a node when the device is operably coupled to the node; and (b)automatically responding with a device identification acknowledgmentmessage from the node to the one or more devices, the deviceidentification acknowledgement message comprising one or more systemattributes.
 2. The system attribute exchange method of claim 1, whereinthe one or more devices comprises one or more Voice-over-IP devices, thedevice identification message is a Voice-over-IP device identificationmessage, and the device identification acknowledgment is a Voice-over-IPdevice identification acknowledgment message.
 3. The system attributeexchange method of claim 2, wherein the one or more system attributescomprises a VLAN identification assigned to Voice-over-IPcommunications.
 4. The system attribute exchange method of claim 2,wherein the node is a switching device, and the one or more systemattributes comprise a switching device identification as well as a portidentification of a port to which the Voice-over-IP device is connected.5. The system attribute exchange method of claim 3, wherein the one ormore Voice-over-IP devices comprise one or more IP phones.
 6. The systemattribute exchange method of claim 3, wherein the Voice-over-IP deviceis operably coupled to the node at the time of initialization of theVoice-over-IP device.
 7. The system attribute exchange method of claim3, wherein the Voice-over-IP device identification message and theVoice-over-IP device identification acknowledgment are AttributeAdvertisement Protocol messages.
 8. The system attribute exchange methodof claim 7, wherein a destination address of the Voice-over-IP deviceidentification message includes a unique medium access control (MAC)address indicative of a system attribute exchange between theVoice-over-IP device and node.
 9. The system attribute exchange methodof claim 3, wherein the Voice-over-IP device identification message issent in response to a node initialization message.
 10. The systemattribute exchange method of claim 9, wherein the node initializationmessage is a switching device initialization message transmitted by aswitching device upon the initialization thereof.
 11. The systemattribute exchange method of claim 1, wherein the system attributecomprises connectivity information associated with the physical localityof the one or more devices.
 12. The system attribute exchange method ofclaim 1, wherein the system attribute comprises connectivity informationpertaining to physical connection of the one or more Voice-over-IPdevices at the node.
 13. The system attribute exchange method of claim12, wherein one or more system attributes are transmitted to a relationdatabase that associates at least one port number to its geographiclocation, whereby the physical location of the one or more devices maybe determined from the IP address of the Voice-over-IP device.
 14. Thesystem attribute exchange method of claim 15, wherein the storage deviceis included in an IP PBX system that cooperates with the Voice-over-IPdevice to provide voice communications.
 15. The system attributeexchange method of claim 1, wherein the node is a switching device. 16.The system attribute exchange method of claim 15, wherein the switchingdevice is adjacent to at least one of the one or more devices.
 17. Thesystem attribute exchange method of claim 15, wherein at least one ofthe one or more devices is a Voice-over-IP device.
 18. The systemattribute exchange method of claim 17, wherein at least one of the oneor more system attributes is a VLAN identification substantiallydedicated to Voice-over IP communication within the network.
 19. Thesystem attribute exchange method of claim 18, wherein the switchingdevice is made aware of the VLAN identification via a VLAN registrationprotocol.
 20. A system attribute exchange system in a distributedcommunications network for automatically providing at least one systemattribute for purposes of configuring Voice-over-IP communications, thesystem comprising: (a) a Voice-over-IP device adapted to automaticallytransmit a Voice-over-IP device identification message when said deviceis operatively coupled to the said network; and (b) a node, operativelycoupled to said network, adapted to automatically transmit aVoice-over-IP device identification acknowledgment message to saiddevice, said Voice-over-IP device identification acknowledgment messageincluding one or more system attributes for said Voice-over-IPcommunications.
 21. The system attribute exchange system of claim 22,wherein at least one system attribute includes a VLAN identification forover which Voice-over-IP communications are conducted.
 22. The systemattribute exchange system of claim 21 wherein the Voice-over-IP deviceidentification message is automatically transmitted when theVoice-over-IP device is operatively coupled to the network.
 23. Thesystem attribute exchange system of claim 23 wherein the Voice-over-IPdevice identification message is automatically transmitted in responseto a switching device initialization message sent upon theinitialization of the switching device.
 24. The system attributeexchange system of claim 20, wherein the at least one of the one or moresystem attributes is a port identifier of a port at said node to whichthe Voice-over-IP device is connected.
 25. The system attribute exchangesystem of claim 24, wherein the port number at which the Voice-over-IPdevice is communicated to a relational database that associates thephysical location of the port with the IP address and extension numberof the Voice-over-IP device, whereby the location of a Voice-over-IPdevice user can be quickly ascertained by emergency response personnel.26. The system attribute exchange system of claim 25, wherein the systemattribute exchange system further includes an IP PBX system comprisingsaid relational database.
 27. The system attribute exchange method ofclaim 8, wherein the MAC address is a broadcast MAC address.
 28. Thesystem attribute exchange method of claim 8, wherein the MAC address isa multicast MAC address.
 29. The system attribute exchange method ofclaim 19, wherein the VLAN registration protocol is the GARP VLANregistration protocol.
 30. The system attribute exchange method of claim12, wherein one or more system attribute are transmitted to a relationdatabase that associates at least one port number to its geographiclocation, whereby the physical location of the one or more devices maybe determined from the MAC address of the Voice-over-IP device.
 31. Thesystem attribute exchange system of claim 24, wherein the port number atwhich the Voice-over-IP device is communicated to a relational databasethat associates the physical location of the port with the MAC addressand extension number of the Voice-over-IP device, whereby the locationof a Voice-over-IP device user can be quickly ascertained by emergencyresponse personnel.
 32. A VLAN advertisement system for a voice-over-IPnetwork, comprising: a first node; and a second node communicating withthe first node over a LAN connection; wherein the first node transmitsto the second node a first message sufficient to identify the first nodeto the second node as an IP phone, and wherein the second node transmitsto the first node a second message responsive to the first messageidentifying a VLAN reserved for voice-over-IP communications.
 33. TheVLAN advertisement system of claim 32, wherein the first node appendsthe identified VLAN to packets transmitted by the first node invoice-over-IP communications.
 34. The VLAN advertisement system of claim32, wherein the first node automatically sends the first message whenthe first node is operably coupled to the second node.
 35. The VLANadvertisement system of claim 32, wherein the first message includes adestination MAC address reserved for VLAN advertisement protocolexchanges.
 36. The VLAN advertisement system of claim 32, wherein thesecond node is a LAN switch.
 37. The system attribute exchange system ofclaim 21 wherein the Voice-over-IP device identification message isautomatically transmitted when the Voice-over-IP device is initializedin the network.